High electron mobility GaN grown under N-rich conditions by plasma-assisted molecular beam epitaxy

An alternative approach is presented for the plasma-assisted molecular beam epitaxy of high-quality GaN. Under N-rich growth conditions, an unexpected layer-by-layer growth mode was found for a wide range of growth temperatures in the GaN thermal decomposition regime (≫750 °C). Consequently, superior surface morphologies with roughness of less than 1 nm (rms) have been achieved. For lightly Si-doped GaN films, room-temperature electron mobilities exceeding 1100 cm²/V s were measured, surpassing the commonly insulating nature of GaN grown under N-rich conditions at low temperature.